PTZ cameras are known in the art, and are becoming more prevalent in the day-to-day security industry. PTZ stands for Pan, Tilt, and Zoom. A PTZ dome security camera differs slightly from a fixed dome camera in that it can move left and right (commonly referring to as pan) or can move up and down (commonly referred to as tilt). These security cameras also include a zoom feature, making an extremely very feature-rich device that can capture images from a distance away from a target location. Sometimes, the PTZ dome camera may be operated manually.
In this instance, the domed camera has a keyboard and a receiver to operate PTZ functions. An operator, like a security guard, may toggle controls on a keyboard or input device to pan, tilt, or zoom and monitor a target. Most PTZ dome security cameras have a receiver device to receive the control signal, however, other dome shaped security devices can include an automated functionality. Under this automated functionality, the PTZ domed camera can automatically view an area or can use triggers to induce movement by the camera, such as using an object tracker, or object recognizer. The PTZ domed camera may take a number of motions. For example, a PTZ security camera may sweep a defined area for a time interval. Additionally, the PTZ camera may detect motion, and based on control logic can reposition the PTZ camera to detect one or more desired conditions. PTZ dome cameras often include a semi-translucent dome that is obscured. This makes it difficult for an individual to notice if they are being recorded by the camera or monitored. PTZ dome camera also may include different configurations, including weatherproofing, day, or night configurations.
The present state of the art in dome video cameras includes associated electrical and mechanical components. The camera generally is mounted on a rotatable platform/section. This platform is covered by a dome, and connects the camera to electrical power, and to a data network of a security system. This is achieved, in some embodiments, by using a multiple conductor mechanical slip ring assembly. Dome cameras are frequently mounted in the ceiling (or on a pole, wall or roof) at a strategic location above the protected premises. The dome camera is rotatably mounted and driven by a pan motor about a generally vertical axis. Dome cameras can rotatably pan about the vertical axis to provide a 360-degree panoramic view of the protected premises. The camera can also be also rotatably mounted and driven by a tilt motor about a generally horizontal axis. This provides a vertically variable field of view. The view is variable from a view just below the horizon to a view more vertically below the dome camera. In this manner, two axes of rotational freedom provide the camera with a versatile capability of viewing many different areas of the protected premises.
The rotatably mounted camera typically includes a mechanical slip ring assembly with a plurality (e.g. 6) of slip rings positioned around a vertical axis of rotation to provide for the transfer of electrical power to all of the components on a rotatable platform/section. The conductors transfer signals from the video camera and its associated electrical circuitry. The conductors also transfer power to the pan and tilt motors and their associated electrical circuitry. The slip ring assembly also carries video signals from the video camera to the video switching or processing system of the security system. The slip ring assembly further carries control and feedback data signals to, and from, the video camera, pan and tilt motors and other associated electrical components. The mechanical slip ring assembly is one of the more expensive components of a dome camera, has a fair reliability, and frequently any repair work is very labor intensive, and may even result in a complete replacement of the camera.
One significant issue is the advent of using digital signals in PTZ camera, and the resulting interference experienced from transmitting a digital signal via the mechanical slip ring assembly. The digital signal may experience interference from an electrical or magnetic source, or from a faulty connection. If one bit of the digital signal is disturbed, then the resulting signal of 512 bits may experience issues that may question the quality or integrity of the digital signal, and the resulting video received. Additionally, communication protocols and the transmission bandwidth are important to quality. The transmission bandwidth of the slip ring assembly is quite limited at 100 Megabits, and this may not be sufficient for all applications.